1. Field of the Invention
The present invention relates to a receiving apparatus which is used while connected to plural antennas, the receiving apparatus receiving a radio signal through the antenna to perform a predetermined process to the received radio signal, the radio signal being transmitted from a body-insertable apparatus inserted into a subject.
2. Description of the Related Art
Recently, a swallowing type encapsulated endoscope makes its appearance in the field of an endoscope. The encapsulated endoscope is provided with an image pickup function and a wireless communication function. After the encapsulated endoscope is swallowed from a mouth of a patient for the purpose of observation (test), the encapsulated endoscope has the function of being moved in a body cavity, e.g., in organs such as a gaster and a small intestine according to peristaltic motion of the organ to sequentially take images until the encapsulated endoscope is naturally discharged from a human body.
The image data taken by the encapsulated endoscope in the body while the encapsulated endoscope is moved in the body cavity is sequentially transmitted to the outside by wireless communication, and the image data is received through a receiving antenna provided outside. Then, the data is reproduced by the receiving apparatus provided outside a subject based on the received radio signal, which allows the image in the body cavity of a patient to be obtained. Even after the patient swallows the encapsulated endoscope and before the encapsulated endoscope is discharged, the patient can freely move because the patient carries the receiving apparatus having the wireless communication function and a memory function. Then, a doctor or a nurse can make a diagnosis by displaying the organ image based on the image data stored in a memory (see Japanese Patent Application Laid-Open No. 2001-231186 (in particular, page 3 and FIG. 1)).
Because the encapsulated endoscope outputs the radio signal while sequentially moved in the body cavity, usually an encapsulated endoscope system has a configuration in which the plural receiving antennas are provided near the subject, e.g., on a subject surface, for receiving the radio signal outputted from the encapsulated endoscope. Therefore, in the conventional encapsulated endoscope system, the radio signal can be received by selecting the receiving antenna most suitable to the reception according to receiving intensity in each receiving antenna, usually by selecting the receiving antenna in which the receiving intensity is highest, and the image in the body cavity can be obtained while receiving sensitivity is kept good.
In the case where the receiving antenna does not perform the function due to a break of the receiving antenna and the like, the image in the body cavity taken by the encapsulated endoscope cannot be obtained. Accordingly, in the general encapsulated endoscope system, it is necessary that presence or absence of the break-down of the receiving antenna is confirmed at every predetermined period or before the encapsulated endoscope is inserted into a subject.
In a performance inspection of the receiving antennas, for example, the receiving apparatus is driven while equipped with the receiving antenna, and a dummy signal having a frequency equal to the radio signal transmitted from the encapsulated endoscope is transmitted to the receiving antenna. Because the transmitted dummy signal is inputted to the receiving apparatus through the receiving antenna, the presence or absence of the break-down of the receiving antenna is detected by determining whether a receiving level detected by the receiving apparatus is higher or lower than a predetermined threshold.
However, when the plural receiving antennas are provided outside the subject, the conventional encapsulated endoscope system has a problem that handling becomes complicated in the performance inspection of the receiving antennas. The problem will be described below.
As described above, the receiving apparatus switches the plural receiving antennas by selecting the receiving antenna having the highest receiving intensity. Accordingly, when the dummy signal is simultaneously transmitted to all the receiving antennas in the performance inspection of the receiving antennas, only the receiving intensity of the specific receiving antenna having the highest receiving intensity is monitored by the receiving apparatus, and the inspection cannot be performed for other receiving antennas except for the receiving antenna having the highest receiving intensity.
Therefore, in the conventional encapsulated endoscope system, it is necessary that the inspection is sequentially performed to the plural receiving antennas. That is, for example, it is necessary that an operation, in which the dummy signal is received for a single receiving antenna while the receiving antenna is arranged near an output antenna for outputting the dummy signal, is sequentially performed to each receiving antenna. Accordingly, when the inspection is performed to the plural receiving antennas, the process becomes very complicated.